Improving partial discharge resistance of hydrophobic epoxy resins with nano-filler dispersion

Outdoor insulation needs materials with weather resistant properties that are superior to those of other insulating materials such as epoxy resins. Silicone rubbers are widely used in these applications, but they are more expensive than other insulating materials. Recently, many studies have been conducted on polymer nanocomposites. We have also demonstrated that nano-filler dispersion improves the insulation properties of epoxy resin. This paper focuses on hydrophobic epoxy resins with the alicyclic group to obtain properties essential for outdoor insulating materials. We prepared hydrophobic epoxy-based nanocomposites containing nano-fillers, and measured the erosion depth and contact angle in order to evaluate their partial discharge resistance and hydrophobicity, respectively. We thus confirmed that the erosion caused by partial discharge was suppressed to less than half with the addition of 5 wt% titanium dioxide or layered silicate. Furthermore, the hydrophobicity of nanocomposite was maintained at a similar level to those of unexposed samples and the contact angle was about 100-110° before and after exposure.